Energy absorbing tether for child safety seat

ABSTRACT

An energy absorbing tether assembly for use with a child safety seat of the type having a pair of spaced apart slots in a shell.

BACKGROUND OF THE INVENTION

This invention relates to child safety seats, and more particularly toan apparatus for mounting child safety seats in vehicles.

Child safety seats typically include a tether which is used to anchorthe upper portion of the seat to a motor vehicle. During a crash, thistether is placed under tension loads as the vehicle decelerates. Thesetethers are usually constructed of a material which exhibits stretch,and therefore provides some energy absorption. However, their mountingis typically rigid and therefore absorption is limited to the stretchavailable in the free length of the tether. Accordingly, there is a needfor a tether which offers increased energy absorption in the event of acrash.

SUMMARY OF THE INVENTION

This need is met by the present invention, which provides, it is anobject to provide a child safety seat tether that is adapted to slipthrough its mountings under crash loads.

It is another object of the invention to provide a child safety seattether that increases the length of tether material available to stretchunder crash loads.

It is another object of the invention to provide a child safety seattether that increases the length of tether material available to stretchunder crash loads.

It is another object of the invention to provide a child safety seattether that includes a convenient carrying handle.

These and other objects of the present invention are achieved in thepreferred embodiments disclosed below by providing a tether assembly foruse with a child safety seat in a vehicle. The seat is of the typehaving a pair of spaced apart slots in a shell. The tether assemblyincludes a length of webbing for routing through the spaced apart slotsin the shell and a first and second slides for disposition along thelength of webbing to retain webbing in one of the spaced apart slots. Anadjuster is connected to the length of webbing and a hook is forsecuring the seat in the vehicle.

According to another preferred embodiment of the invention, the firstand second slides are three bar slides.

According to another preferred embodiment of the invention, the lengthof webbing is flexible.

According to another preferred embodiment of the invention, the webbingis routed through the slides to permit slippage.

According to another preferred embodiment of the invention, the portionof the length of webbing forming the handle is folded over and stitchedtogether.

According to another preferred embodiment of the invention, movement ofthe slides is limited by the shell.

According to another preferred embodiment of the invention, stitching isincluded for frangibly connecting the length of webbing to itself on theback side of the shell.

According to another preferred embodiment of the invention, the slidesare larger than the slots.

According to another preferred embodiment of the invention, a tetherassembly for use with a child safety seat of the type having a pair ofspaced apart slots in a shell includes a first length of webbing forrouting through an adjuster and a second length of webbing fixed to theadjuster. A first slide is for disposition along the first length ofwebbing to retain webbing of the first length in one of the spaced apartslots and a second slide for disposition along the second length ofwebbing to retain webbing of the second length in the other of thespaced apart slots.

According to another preferred embodiment of the invention, the assemblyincludes a hook having an opening for receiving one of the lengths ofwebbing.

According to another preferred embodiment of the invention, the seat isfor use in a vehicle and the hook is for securing the seat to thevehicle.

According to another preferred embodiment of the invention, the firstand second slides are three bar slides.

According to another preferred embodiment of the invention, the lengthsof webbing are routed through the slides to permit slippage.

According to another preferred embodiment of the invention, the slidesare larger than the slots.

According to another preferred embodiment of the invention, the assemblyincludes stitching for frangibly coupling portions of the length ofwebbing together on a back side of the shell.

According to another preferred embodiment of the invention, a tetherassembly for use with a child safety seat of the type having a pair ofspaced apart slots in a shell includes a first length of webbing forrouting through an adjuster and a second length of webbing fixed to theadjuster. A first slide is for disposition along the first length ofwebbing on a front side of the shell to retain webbing of the firstlength in one of the spaced apart slots and a second slide is fordisposition along the second length of webbing on a front side of theshell to retain webbing of the second length in the other of the spacedapart slots. The assembly further includes stitching for permanentlycoupling portions of the first length together to retain the first slideon the front side of the shell and stitching for permanently couplingportions of the second length together to retain the second slide on thefront side of the shell.

In another preferred embodiment of the invention, the assembly furtherincludes a hook having an opening for receiving the second length ofwebbing.

In another preferred embodiment of the invention, the assembly includesstitching for frangibly coupling portions of the first length of webbingtogether and portions of the second length of webbing together on oneside of the shell to provide slack loops.

In another preferred embodiment of the invention, the slack loops areprovided on the front side of the shell.

In another preferred embodiment of the invention, the slack loops areprovided on the back side of the shell.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention may be best understood by reference to the followingdescription taken in conjunction with the accompanying drawing figuresin which:

FIG. 1 is a perspective view of a child safety seat including a tetherconstructed according to a first embodiment of the present invention;

FIG. 2 is a rear perspective view of the tether of FIG. 1 attached to achild safety seat;

FIG. 3 is a rear view of the tether of FIG. 1 attached to a child safetyseat;

FIG. 4 is a front view of the tether of FIG. 1 attached to a backshellof a child safety seat;

FIG. 5 is a perspective view showing the tether of FIG. 1 being used tocarry a child safety seat;

FIG. 6 is a perspective view of a seat with the tether of FIG. 1 afteran impact;

FIG. 7 is a perspective view of a tether constructed in accordance witha second embodiment of the invention;

FIG. 8 is another perspective view of the tether of FIG. 7;

FIG. 9 is another perspective view of the tether of FIG. 7, showing arouting thereof;

FIG. 10 is a schematic cross-sectional view of a slide of the tether ofFIG. 7, showing the routing in more detail;

FIG. 11 is a front view of the tether of FIG. 7 attached to a backshellof a child safety seat;

FIG. 12 is a rear view of the tether of FIG. 7 attached to a childsafety seat;

FIG. 13 is a rear view of a tether constructed in accordance withanother embodiment of the invention, attached to a child safety seat;

FIG. 14 is a front view of the tether of FIG. 13;

FIG. 15 is an enlarged front view of a portion of the tether of FIG. 13;

FIG. 16 is a schematic cross-sectional view of a slide shown in FIG. 13,showing a routing of webbing therethrough; and

FIG. 17 is a schematic cross-section view of an alternative routing ofwebbing through a slide.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings wherein like reference numerals indicatethe same components throughout the various views, FIGS. 1 and 2illustrate a first exemplary embodiment of a tether 10 for use with achild safety seat. Its main component is a single length of webbing 12,for example nylon or other suitable flexible material. A free end 14 ofthe webbing 12 is routed through an adjuster 16 of a known type, andthen extends laterally to form a loop 18. A hook 20 slides along thisloop 18. The webbing 12 is routed through a first slide 22 of a knowntype, such as a 3-bar slide, and then laterally across to a second slide24, and finally terminates at a fixed connection to the adjuster 16. Theportion of the webbing 12 between the slides 22 and 24 is foldedtogether and sewn to define an oval or round cross-section carryinghandle 26. An internal form such as padding (not shown), which may beenergy absorbing, may be used to help define the handle shape. Anexternal form may also be added to the webbing that defines the carryinghandle 26, which could be made of an energy absorbing material (notshown). Lines of stitching 25 may be applied to secure the loop 18 tothe carrying handle 26 to prevent the carrying handle 26 from slippingbeyond a desired position when it is used as a handle.

FIGS. 3 and 4 show how the tether 10 may be mounted to a child safetyseat 28 which includes a backshell 30. Portions of the webbing 12 arerouted through laterally-spaced-apart slots 32 and 34 in the backshell30, which are large enough to accept the webbing 12 but smaller than thesurface area of the slides 22 and 24. The slides 22 and 24 are disposedon the front side of the backshell 30 and are oriented so as to resistbeing pulled through the slots 32 and 34.

FIG. 5 shows the carrying handle 26 being used to transport the childsafety seat 28. As the carrying handle 26 is pulled, the webbing 12tends to slip through the slides 22 and 24 such that the loop 18effectively becomes shorter. The stitching lines 25 limit this motion.

In use, child safety seat 28 is secured to a vehicle anchor point (suchas an upper LATCH anchor, not shown). The free end 14 of the webbing 12is then pulled through the adjuster 16 to set the length of the loop 18as desired. In an accident, tension loads will be placed on the loop 18and the hook 20 as the vehicle decelerates. The webbing 12 stretches aswith a conventional tether. Upon impact, the stitching 25 that preventsthe webbing 12 from slipping when the seat 28 is carried breaks. Thisallows the webbing 12 to slip through the slides 22 and 24, absorbingsome energy by overcoming friction and allowing the length of the loop18 to increase while shortening the carry handle 26. The total slippageis restricted by the carrying handle 26 stopping against the backshell30 (see FIG. 6).

FIGS. 7-10 illustrate a second exemplary embodiment of a tether 110 foruse with a child safety seat. It is similar in general construction tothe tether 10 described above, and its main components are first andsecond portions 112A and 112B of webbing, for example nylon or othersuitable flexible material. A free end 114 of the first webbing portion112A is routed through an adjuster 116 of a known type, and then extendslaterally to form a loop 118. A hook 120 slides along this loop 118. Thefirst webbing portion 112A is routed through a first slide 122 of aknown type, such as a 3-bar slide, and then doubled back to form a firstpigtail 121, with an end doubled over as a stop 125 The second webbingportion 112B has one end anchored at a fixed connection to the adjuster116. The other end is routed through a second slide 124, and thendoubled back to form a second pigtail 123, with an end doubled over as astop 127. Lines of stitching 129 (see FIG. 7) may be provided in thewebbing 112 to secure the pigtails 121 and 123 to the webbing 112 andthus prevent the slides 122 and 124 from moving along the webbing 112prior to an impact.

The webbing portions 112A and 112B are routed through the slides 122 and124 in a configuration which provides adequate friction to the webbing112 during sliding. This routing is depicted schematically in FIG. 10.

FIGS. 11 and 12 show how the tether 110 may be mounted to a child safetyseat 28 which includes a backshell 30. The webbing portions 112A and112B are routed through laterally-spaced-apart slots 132 and 134 in thebackshell 30, which are large enough to accept the webbing 112 butsmaller than the surface area of the slides 122 and 124. The slides 122and 124 are disposed on the front side of the backshell 30 and areoriented so as to resist being pulled through the slots 132 and 134. Thepigtails 121 and 123 extend freely on the front side of the backshell 30(i.e. inside the seat 28).

In use, child safety seat 28 is secured to a vehicle anchor point (suchas an upper LATCH anchor, not shown). The free end 114 of the firstwebbing portion 112A is then pulled through the adjuster 116 to set thelength of the loop 118 to the desired tension. In an accident, tensionloads will be placed on the loop 118 and the hook 120 as the vehicledecelerates. The webbing 112 stretches as with a conventional tether.The webbing portions 112A and 112B will also slip through the slides 122and 124 when the stitching 129 breaks, tending to increase the length ofthe loop 118 and shorten the pigtails 121 and 123. This absorbs someenergy by overcoming friction and allowing the length of the loop 118 toincrease. The total slippage is restricted by the stops 125 and 127contacting the backshell 30 (see FIG. 12).

FIGS. 13-15 illustrate a third exemplary embodiment of a tether 210 foruse with a child safety seat. It is similar in general construction tothe tether 110 described above, and its main components are first andsecond portions 212A and 212B of webbing, for example nylon or othersuitable flexible material. A free end 214 of the first webbing portion212A is routed through an adjuster 216 of a known type, and then extendslaterally to form a loop 218. A hook 220 slides along this loop 218. Thefirst webbing portion 212A is routed through a first slide 222 of aknown type, such as a 3-bar slide (see FIG. 14). The second webbingportion 212B has one end anchored at a fixed connection to the adjuster216. The other end is routed through a second slide 224.

The webbing portions 212A and 212B are routed through the slides 222 and224. FIG. 16 is a schematic depiction of the routing of the secondwebbing portion 212B, which is representative of the routing of theother webbing portion 212A. The second webbing portion 212B is loopedover the central bar of the second slide 224 and anchored thereto, forexample by using a strong pattern of permanent stitching depicted at213. The free end of the webbing portion 212B is formed into a slackloop 215 which is secured to the remainder of the webbing portion 212Bby a frangible connection such as a single stitching line, depicted at217. A similar slack loop 219 (see FIG. 14) is formed in the firstwebbing portion 212A.

FIG. 15 shows how the tether 210 may be mounted to a child safety seat28 which includes a backshell 30. The webbing portions 212A and 212B arerouted through laterally-spaced-apart slots 232 and 234 in the backshell30, which are large enough to accept the webbing 212 but smaller thanthe surface area of the slides 222 and 224 The slides 222 and 224 aredisposed on the front side of the backshell 30 and are oriented so as toresist being pulled through the slots 232 and 234 The slack loops 215and 219 and extend freely on the front side of the backshell 30 (i.e.inside the seat 28).

In use, child safety seat 28 is secured to a vehicle anchor point (suchas an upper LATCH anchor, not shown). The free end 214 of the firstwebbing portion 212A is then pulled through the adjuster 216 to set thelength of the loop 218 to the desired tension. In an accident, tensionloads will be placed on the loop 218 and the hook 220 as the vehicledecelerates. The webbing 212 stretches as with a conventional tether.The webbing portions 212A and 212B will also slip through the slides 222and 224 when the frangible connection 217 breaks, tending to increasethe length of the loop 218 and pull out the slack loops 215 and 219.This absorbs some energy by overcoming friction and allowing the lengthof the loop 218 to increase. The total slippage is restricted by thesecure anchorage of the webbing portions 212A and 212B to the slides 222and 224.

FIG. 17 is a schematic depiction of a tether 210′ similar to the tether210 but using an alternative routing of webbing 212′. In thisembodiment, webbing 212′ is looped over the central bar of the a slide224′ and anchored thereto, for example by using a strong pattern ofpermanent stitching depicted at 213′. Downstream of the slide 224′, thewebbing 212′ is formed into a slack loop 215′ which is secured to theremainder of the webbing 212′ by a frangible connection such as a singlestitching line, depicted at 217′. When anchored in a backshell 30, theslack loop 215′ and the free end of the webbing 212′ both extend fromthe rear side of the backshell 30. In an accident, the frangibleconnection 217′ will break, tending to increase the length of the tether210′ and pull out the slack loop′. This absorbs some energy by allowingthe length of the webbing 212′ available for stretching to increase. Thetotal slippage is restricted by the secure anchorage of the webbing 212′to the slide 224′.

An important benefit of the tethers described above over prior arttethers is the ability of the webbing to slip through the slides and/orincrease its length upon impact. This provides energy absorptionbenefits in two ways. First, energy is used to overcome friction as thewebbing slips through the slides as described above. Second, by allowingmore webbing to slip through the slides, the total length of webbingthat is available to stretch is greater than the amount available ifslipping did not occur. More webbing stretch or elongation allows forgreater energy absorption.

The foregoing has described an energy-absorbing tether for a childsafety seat. While specific embodiments of the present invention havebeen described, it will be apparent to those skilled in the art thatvarious modifications thereto can be made without departing from thespirit and scope of the invention. The principles of allowing webbing toslide with frictional resistance and/or of providing additional tetherlength for stretching in a crash are not limited to a tether straphaving two mounting points. It may be applied to a tether having asingle mounting point, or other kinds of straps and harnesses used withchild safety seats. Accordingly, the foregoing description of thepreferred embodiment of the invention and the best mode for practicingthe invention are provided for the purpose of illustration only and notfor the purpose of limitation.

1. A tether assembly for use with a child safety seat in a vehicle, the seat of the type having a pair of spaced apart slots in a shell, the tether assembly comprising: (a) a length of webbing for routing through the spaced apart slots in the shell; (b) a first slide for disposition along the length of webbing to retain webbing in one of the spaced apart slots; (c) a second slide for disposition along the length of webbing to retain webbing in the other of the spaced apart slots; (d) an adjuster connected to the length of webbing; and (e) a hook for securing the seat in the vehicle.
 2. An assembly according to claim 1 wherein the first and second slides are three bar slides.
 3. An assembly according to claim 1 wherein the length of webbing is flexible.
 4. An assembly according to claim 1 wherein the webbing is routed through the slides to permit slippage.
 5. An assembly according to claim 1 wherein a portion of the length of webbing is folded over and stitched together to form a handle.
 6. An assembly according to claim 1 wherein movement of the slides is limited by the shell.
 7. An assembly according to claim 1 further including stitching for frangibly connecting the length of webbing to itself on the back side of the shell.
 8. An assembly according to claim 1 wherein the slides are larger than the slots.
 9. A tether assembly for use with a child safety seat of the type having a pair of spaced apart slots in a shell, the assembly comprising: (a) a first length of webbing for routing through an adjuster; (b) a second length of webbing fixed to the adjuster; (c) a first slide for disposition along the first length of webbing to retain webbing of the first length in one of the spaced apart slots; and (d) a second slide for disposition along the second length of webbing to retain webbing of the second length in the other of the spaced apart slots.
 10. An assembly according to claim 9 further comprising a hook having an opening for receiving one of the lengths of webbing.
 11. An assembly according to claim 10 wherein the seat is for use in a vehicle and the hook is for securing the seat to the vehicle.
 12. An assembly according to claim 9 wherein the first and second slides are three bar slides.
 13. An assembly according to claim 9 wherein the lengths of webbing are routed through the slides to permit slippage.
 14. An assembly according to claim 13 wherein the slides are larger than the slots.
 15. An assembly according to claim 1 further including stitching for frangibly coupling portions of the length of webbing together on a back side of the shell.
 16. A tether assembly for use with a child safety seat of the type having a pair of spaced apart slots in a shell, the assembly comprising: (a) a first length of webbing for routing through an adjuster; (b) a second length of webbing fixed at one end to the adjuster; (c) a first slide for disposition along the first length of webbing on a front side of the shell to retain webbing of the first length in one of the spaced apart slots; (d) a second slide for disposition along the second length of webbing on a front side of the shell to retain webbing of the second length in the other of the spaced apart slots; (e) stitching for permanently coupling portions of the first length together to retain the first slide on the front side of the shell; and (f) stitching for permanently coupling portions of the second length together to retain the second slide on the front side of the shell.
 17. A tether assembly according to claim 16 further comprising a hook having an opening for receiving the second length of webbing.
 18. A tether assembly according to claim 17 further comprising stitching for frangibly coupling portions of the first length of webbing together and portions of the second length of webbing together on one side of the shell to provide slack loops.
 19. A tether assembly according to claim 18 wherein the slack loops are provided on the front side of the shell.
 20. A tether assembly according to claim 18 wherein the slack loops are provided on the back side of the shell. 